Cannot distribute via Testflight using fastlane in Jenkins

I have been struggled to distribute our beta software via fastlane. It used to say that I put an incorrect username or password. But I already assigned the environment variable like below.

env["FASTLANE_USER"] = "xxxxxxx@xxxxx.com"
env["FASTLANE_PASSWORD"] = "xxxxxxxxx"

In my case I just added another line to reassign the env["FASTLANE_PASSWORD"] before it uploads the file to Testflight. By the way I feel that it takes too much time to process a build in Apple Testflight. So I have thought about moving to another service for my beta software release.